PURPOSE: To improve the saturation of yellow glass, to stabilize color tones and to approximate the coefft. of thermal expansion to the coefft. of thermal expansion of Jena 16III of standard thermometer glass by specifying the CdS and Se content ratios of yellow glass, adding F to the glass and specifying the compsn. thereof.

CONSTITUTION: The yellow core disposed with the yellow glass layer having the compsn. consisting, by weight %, of 60-70 SiO2, 3-10 Al2O3, 7-18 Na2O, 1-5 K2O; 1-8 CaO, O-MgO, 1W8 ZnO, 1-5 B2O3, 0.1-2 CdS, 0<Se≤1, and 0.1-3F, having 10-100 CdS/Se ratio and 80-96×10-7/°C coefft. of thermal expansion is provided to the thermometer. This yellow core thermometer has the yellow core disposed with the yellow glass which has the coefft. of thermal expansion approximate to the coefft. of thermal expansion of the Jena 16III and is stable in color tones with the sufficient saturation and, therefore, the moldability is good, the height position of the mercurial column is easily checkable and the temp. measurement is easy.